At Oxford, a Battery That's Lasted 175 Years -- So Far

sarahnaomi writes There sits, in the Clarendon Laboratory at Oxford University, a bell that has been ringing, nonstop, for at least 175 years. It's powered by a single battery that was installed in 1840. Researchers would love to know what the battery is made of, but they are afraid that opening the bell would ruin an experiment to see how long it will last. The bell's clapper oscillates back and forth constantly and quickly, meaning the Oxford Electric Bell, as it's called, has rung roughly 10 billion times, according to the university. It's made of what's called a "dry pile," which is one of the first electric batteries. Dry piles were invented by a guy named Giuseppe Zamboni (no relation to the ice resurfacing company) in the early 1800s. They use alternating discs of silver, zinc, sulfur, and other materials to generate low currents of electricity.

Comments

Bullshit

[Anonymous Coward]

From The Fucking Article

"You'd think it'd be annoying as hell for a bell to be going off, constantly, for 175 years—but the voltage left in the battery is so low that the human ear can't actually hear the ringing. Instead, the clapper oscillates back and forth between the bell constantly, which you can see happening in this video. At this point, the experiment is more of a curiosity than anything—Croft says that the battery pulls 1 nanoAmp each time it oscillates between the bell’s sides, which is an exceedingly low amount of energy."

Re:Bullshit

[Solandri]

From a little googling, the voltage between the terminals is 2 kV. The clapper draws about 1 nA.

(175 years) * (2 kV) * (1 nA) = 11045 Joules ]

Which in terms most people can relate to is about 3 Watt-hours, or about the same as a singe AA battery. Not very impressive.

Re:Bullshit

[Anonymous Coward]

9V batteries have more than enough current available to stop someone's heart if put in series. If you have 400-1000V DC worth that's more than enough to kill someone. Be glad that a little knowledge didn't get someone killed.

Re:Bullshit

[Antique Geekmeister]

I do believe that you're thinking of "mA", not "mV". 15 mV is even less than the trigger voltage of an ordinary nerve cell. A few mA, through the right nerves of the heart at the right moment, can _decouple_ the heart's normal pulsing rhythm, causing fibrillation. It's well worth a bit of research into how "defibrillators" work: I'm afraid I'm old enough that I have some acquaintances with implanted pacemakers to control just that sort of problem.

Re:Bullshit

[rgbatduke]

Actually, you can kill yourself with a single 9 V battery -- or the 12 V battery of your car. One man did:

http://darwinawards.com/darwin...

The computation goes as follows. The issue, as several people have pointed out, is that it is current across the heart that causes defibrillation (basically interrupting the heart's natural rhythm so that it pulses chaotically), not a matter of cooking the person (which will also work, BTW, but isn't the most common cause of electrical shock deaths). It isn't even the case that more current is always worse -- there appears to be a range of currents that are more toxic than others. A brief explanation of this is here:

https://www.physics.ohio-state...

The maximally toxic range of currents across the thorax is empirically 0.1 to 0.2 amps. Below that it isn't enough to defibrillate, above that the heart muscle clamps all the way which means that when the current is removed it is actually more likely that it can with help or will on its own restore a normal rhythm.

The internal resistance of the human body once you introduce probes through the comparatively insulating skin is around 100 ohms. A 9V battery across ~100 ohms makes a thoracic current of roughly 0.1 amp, right at the start of the maximally fatal range. The Darwin above was given because an idiot didn't believe this and stuck probes through his skin to "prove" that it wasn't so.

Personally I've experienced shocks from 12 V car batteries when screwing around with them on rainy nights with salt water on my hands. That's another good way of reducing skin resistance. I didn't take the hit across the torso, but it was every bit as painful as a 110V shock through dry skin -- more so, actually -- and caused my muscles to contract like lightning.

None of this is actually news -- it has been known as long as there has been electricity, because people have been killing themselves accidentally with electricity just that long. My scout leader 50 years ago worked for GE (as an inventor, actually -- one of the people who invented the photodiode controlled light). He taught me that long ago to ground one finger and then brush another finger of the same hand against any possible hot wire so that you find out with a jolt across your hand, not through your torso. Hand to foot, hand to hand, not so good. People used to kill themselves all the time touching hot electrical switches while standing in wet feet on bathroom floors before ground fault circuits were invented and mandated by code.

None of which has much to do with TFA, but it is good to know if you work at all with electricity. Physicists need to know it just to be able to teach it to their students so THEY don't kill themselves accidentally one day. It isn't the voltage that kills you, it's the current, and it doesn't take much current to do the job (or much voltage to create a fatal current).

Re:Bullshit

[ceoyoyo]

Action potentials are a bit funny. They're not actually movements of electrons down a wire like we're used to thinking about, but rather propagating waves of changes in the way cellular pumps move heavy ions through the cell membrane. Action potentials provide essentially no long-distance current, for example.

If you applied 15 mV across the SA node (the heart's built in pacemaker) at just the right time in the cardiac sequence you might be able to interfere enough to stop the organized contraction. There's a lab at my university that's been looking at analyzing chaotic heart contractions in order to use very small, very well-timed pacemaker signals, to correct them.

You would absolutely have to do it internally though ("applied directly to the heart"). The human body is basically a bag of salt water, which conducts quite well (about 300 Ohm from head to toe IIRC) surrounded by skin, which is a pretty good insulator. So if you want to electrocute someone, stab the electrodes in first.

The Karpen Pile

[psergiu]

http://en.wikipedia.org/wiki/N...

The Karpen Pile, currently on display at the Dimitrie Leonida National Technical Museum in Bucharest, Romania, still gives out 1V after 60 years.

This one has a glass enclosure so it can be studied.

Hold your horses

[Dan East]

Let's put this in perspective. The only "amazing" thing here is simply that the chemicals used in the battery are very stable. The amount of energy we're talking about is very, very low.

FTA, it takes around 1 nanoampere to ring the bell once. It rings around around 2 Hz. Thus it takes 2 nanoampere a second, which works out to 7200 nanoampere-hours.

So let's see how long a AA battery could run that bell. The better AAs produce 3 amp-hour of power. That is 3000000000 nanoamperes. 3000000000 / 7200 gives us 416,666 hours, which is 47.56 years. So if we could somehow spread the power of a AA out over time so the chemicals didn't break down, it could power that bell for 47.56 years. A single D battery has 12 amp-hours of power (4 times that of a AA), thus it could run the bell for 190 years.

We're not talking about much power whatsoever - simply that the chemicals and construction of the battery are such that it has not degraded that much just through time alone.

Re:Hold your horses

[quenda]

FTA, it takes around 1 nanoampere to ring the bell once. It rings around around 2 Hz. Thus it takes 2 nanoampere a second, which works out to 7200 nanoampere-hours.

Ouch! Your bad maths is making my head hurt. Amp is a measure of current, not energy or charge.
  A nA is one nano-couloumb per second. WTF does "nanoampere a second" even mean? Current acceleration?
  One nano-Amp for an hour is precisely one nano-Amp hour, duh!
Better known as 3.6 microcoulombs. At 2kV, it is 7.2 milli-joules of energy.
For that idiocy you get a +5? Mods need to stay in school.

The better AAs produce 3 amp-hour of power. That is 3000000000 nanoamperes.

FFS! First you equate amp-hours with power, and then you equate it with amps. Where did the time unit go?
Your 3AHr battery at one nano-Amp will last 3 x 10 to the 9 hours, or 342,000 years. (neglecting internal leakage :-)
Of course you will need a few of them in series to equal the 2kV of the Oxford Bell.
What has happened to /.?

(disclaimer: After that rant, I'm almost certain to have made an error myself.)

Re:Interstellar missions...

[arth1]

Deep space tends to be very cold

This is misleading at best.

Space in itself is a near vacuum, which (a) has no temperature of its own, and (b) is a wonderful insulator. Which is why a thermos uses vacuum for insulation.
Objects in space can become very cold over long time spans, as heat slowly radiates away without being replenished at the same rate. But space itself doesn't cool them down.

Voyager 1, which is the operative craft that's been in service the longest and receives the least amount of heat from the sun is, after most of the heaters have been turned off to conserve energy, running at around -80C temperatures. That's a veritable furnace compared to other older objects in space that have radiated away more heat over much longer time.

Also, you say "chemical batteries". Well, yes, it is, but this is a dry battery. The composition doesn't change with colder temperatures, unlike wet batteries where liquids freeze. Dry batteries don't have that problem, which is why it is interesting.